The major objective in this research is to make significant contributions to organic chemistry and medicine through synthetic studies on highly physiologically active complex natural products, including neurotoxins and antibiotics. Namely, we believe that the power of organic chemistry, especially organic synthesis, is most efficiently extended on challenging complex systems, and much of the progress of medicine certainly depends upon the extension of such power of organic chemistry. Related to the major one, it is also our specific objective to develop practical and efficient syntheses of certain natural products and their analogs which have high physiological activities, but are not available in appreciable amount from natural sources. These studies are again expected to bring the progress in medicine.